Skylights provide desirable natural lighting for building interiors, increasing visual attractiveness and reducing energy usage.
A skylight includes a rooftop element through which sunlight enters the skylight structure, a diffuser at the building interior, and a channel between the rooftop element and diffuser to convey light from the first to the second.
One configuration of such a skylight is a tubular skylight, in which the channel is a tube, often of circular cross-section, which may have a reflective interior surface.
Some tubular skylights are provided with pre-assembled light tubes. However, provision of pre-assembled light tubes may be disadvantageous, in that they are bulky and therefore more difficult and more expensive to transport. Furthermore, because of the thin metal with which they are often constructed, pre-assembled light tubes may be damaged during shipment or from handling.
Other designs of light tubes call for construction of the light tube on-site. Such designs are provided with the light tube initially as an unrolled sheet of material. At the installation site, the light tube is fabricated by rolling the sheet upon itself, overlapping two opposed edges, then installing screws through the overlapped edges. While offering certain advantages, such a design likewise suffers certain disadvantages. For example, it has been found that the force of feeding a screw through the rolled, overlapped sheet material is prone to deform the sheet material. Furthermore, this design can be assembled with the light tube inadvertently fixed at an improper diameter. Additionally, labor costs on-site are often the most expensive of those involved in building construction, but this design increases assembly time on-site and therefore increases labor costs.
Installation of a tubular skylight may proceed as follows. With new construction, the building is first “weathered in,” including installation of the exterior cover for the skylight at the building roof. Second, the interior ceiling is installed. It is only after those two steps are completed that a light tube itself is installed between the exterior cover and the interior ceiling. Similarly, in retrofitting a tubular skylight to an existing structure, the exterior cover would first be installed, then the interior diffuser would be installed in a room interior ceiling. Thereafter, a light tube would be configured between those two elements. In both instances, at least two challenges may be presented. First, precise placement of the diffuser relative to the exterior cover may be misjudged. Second, the precise length needed for the light tube between those two elements may be misjudged. In either circumstance, it would be desirable to have a light tube the components of which could provide side-to-side adjustment of the lower end relative to the upper end for those cases in which the diffuser has not been positioned exactly, relative to optimal placement with regard to the location of the exterior cover. Furthermore, it would be desirable to have a light tube that could be easily fabricated and assembled within the space, yet telescope upon itself so as to fully and completely span the distance between those two elements.